Google publie une liste des erreurs les plus courantes rencontrées dans les flux RSS:
Extraits:

15.6% Input claims to be UTF-8 but contains invalid characters.
14.9% Opening and ending tags mismatch
13.9% An undefined entity is used (e.g.   in an XML document without importing the HTML set)
7.8% Documented expected to begin with a start tag, but no < was found
5.7% Disallowed control characters present
5.5% Extra content at the end of the document
4.2% Unterminated entity reference (missing semi-colon)
4.2% Unquoted attribute value
3.8% Premature end of data in tag (truncated feed)
3.3% Naked ampersand (should be represented as &)
2.1% XML declaration allowed only at the start of the document
1.8% Namespace prefix is used but not defined
0.75% Comment not terminated
0.64% Attribute without value
0.17% Unescaped < not allowed in attributes values
0.11% Malformed numerical entity reference
0.11% Unsupported/invalid encoding
0.10% Comment must not contain '--'
0.10% Attribute defined more than once
0.07% Char out of allowed range
0.03% Comment not terminated
0.02% Sequence ]]>

Ces erreurs rendent les flux illisibles ! A bon entendeur …

Via GoogleReaderBlog